The GPO Kontakt 2 Player Update is available from NI and is causing some unforseen problems with the installation and usage. I have put together a step by step Howto to try and deal with the authorisation and installation of the update. The Mac howto will be available shortly.
I can't seem to get K2 working with GPO. I followed the directions (except for the part about registering K2 online -- I had to save the HTML and perform the registration from a computer that was connected to the internet). I imported the resulting .naf file from the NI website, but my K2 doesn't look like the one in your document (the GPO graphics don't show up). When I try to open a sound, it says they're not valid in K2. Everything works fine in the old GPO player. Any ideas?
My guess is you can simply uninstall Garritan Personal Orchestra and delete the library files, if you are positive, you won't need GPO KP1 anymore. Or you can create a hardlink to the .nks files instead of copying them.